Present telecommunication systems include many wireless networking systems for both voice and data communication. An overview of several of these wireless networking systems is presented by Amitava Dutta-Roy, Communications Networks for Homes, IEEE Spectrum, December 1999 at 26. Therein, Dutta-Roy discusses several communication protocols in the 2.4 GHz band, including IEEE 802.11 direct-sequence (DS) and frequency-hopping (FH) protocols. These protocols, however, were initially developed for cellular telephony. A disadvantage, therefore, of these protocols is the high overhead associated with their implementation. Id. at 31. A less complex wireless protocol known as the Shared Wireless Access Protocol (SWAP) also operates in the 2.4 GHz band. This protocol has been developed by the HomeRF Working Group and is supported by North American communications companies. The SWAP protocol uses frequency-hopping spread-spectrum technology to produce a data rate of 1 Mb/s. Another less complex protocol is named Bluetooth after a 10th century Scandinavian king who united several Danish kingdoms. This protocol also operates in the 2.4 GHz band and advantageously offers short-range wireless communication between Bluetooth devices without the need for a central network.
The Bluetooth protocol operates in the 2.4 GHz ISM band and provides a 1 Mb/s data rate with low energy consumption for battery operated devices. The current Bluetooth protocol provides a 10 meter range and an asymmetric data transfer rate of 721 kb/s. The protocol supports a maximum of three voice channels for synchronous, CVSD-encoded transmission at 64 kb/s. The Bluetooth protocol treats all radios as peer units except for a unique 48-bit address. At the start of any connection, the initiating unit is a temporary master. This temporary assignment, however, may change after initial communications are established. Each master may have active connections of up to seven slaves. Such a connection between a master and one or more slaves forms a piconet. Link management allows communication between piconets, thereby forming scatternets. Typical Bluetooth master devices include cordless phone base stations, local area network (LAN) access points, laptop computers, or bridges to other networks. Bluetooth slave devices may include cordless handsets, cell phones, headsets, personal digital assistants, digital cameras, or computer peripherals such as printers, scanners, fax machines and other devices.
The Bluetooth protocol uses time-division duplex (TDD) to support bi-directional communication. Spread-spectrum technology or frequency diversity with frequency hopping permits operation in noisy environments and permits multiple piconets to exist in close proximity. The frequency hopping scheme permits up to 1600 hops per second over 79 1-MHz channels or the entire ISM spectrum. Various error correcting schemes permit data packet protection by ⅓ and ⅔ rate forward error correction. In addition, Bluetooth uses retransmission of packets for improved reliability. These schemes help correct data errors but at the expense of bandwidth. Moreover, the retransmission method is not useful for voice calls due to the limited permissible delay. Finally, the existing Bluetooth protocol fails to exploit spatial diversity as developed for wideband code division multiple access (WCDMA) systems and disclosed by Dabak et al. in U.S. patent application Ser. No. 09/373,855, filed Aug. 13, 1999. These diversity techniques have proven effective for improved transmit range and reduced bit error rates and interference for WCDMA.